The jeans referred to in the second half of the title "The Sisterhood of the Traveling Pants" are discovered in a thrift store by the four 16-year-old girls referred to in the other half. They have magical properties, the pants do, in that they fit each girl perfectly despite wide variances in the girls' figures. Many women would kill -- and I mean literally take the life of another person -- to have pants this forgiving and flattering.

The girls, all born the same week and friends ever since in their Washington, D.C., suburb, are about to spend the summer in four different places before reuniting for the senior year in high school. Since the pants are clearly enchanted, they agree to pass them around, each girl having them for a week before sending them on to the next wearer. The pants are not to be washed (lest the magic properties be stain-lifted away), and letters describing the girls' exploits in the pants are to accompany them on their journey, so that all may be edified by the blue jeans' beneficence.

In other words, this is a movie about what four girls did on their summer vacations, and the pants are irrelevant. Based on Ann Brashares' bestselling novel that I have not read (nor indeed even heard of until a couple weeks ago), "Sisterhood" deserves credit for appealing to its core audience of teenage girls without pandering to them. It deals with mature themes such as terminal illness and teen sexuality, and even gets into one girl's introspective dilemma of realizing she is not the person she thought she was, yet keeps a patina of fluffiness over the whole thing. It's a serious movie, but a fun one.

Director Ken Kwapis, a TV veteran, has his hands full with four separate stories that span the globe. Lena (Alexis Bledel), the shy and quiet one, has gone to Greece for the summer, living with her grandparents and learning the ways of the Old Country (and, it should be noted, falling in love with a hunky fishmonger). Her opposite is Bridget (Blake Lively), blond, competitive, athletic and uninhibited, in Mexico for a soccer camp (and, it should be noted, falling in love with a hunky camp counselor). Then there is Tibby (Amber Tamblyn), with blue streaks in her hair and a Goth-y sort of fake cynicism, stuck at home working at a quasi-Wal-Mart store, filming her documentary -- "an ode to lives of quiet desperation" -- in her spare time. And finally there is Carmen (America Ferrera), our narrator and a would-be writer, Latina and bulky, living with her father and his very Caucasian family in South Carolina for the season.

These characters are more fully realized than you'd expect them to be, with multiple tertiary characters -- a non-communicative father here, a small-town co-worker there -- helping to flesh them out. Thanks to winning performances from each of the leads, you get the sense that these are real people and not just lists of character traits.

Where the film struggles a bit is in the end, when it obsessively goes around and wraps up every loose end, including minor ones where the audience's guess at how it would end was probably adequate. The consequence of this is that the film wears out its welcome, going on for at least 15 minutes more than it needs to before it finally sees fit to throw the pants in the laundry and call it a day.